Automatic Transmission Control Module problems of the 2000 GMC Yukon

My 2000 Yukon has had problems with the engine stalling during braking and turns since I bought it in 2001 with 10,000 miles on it. I took it in to the dealership several times while still under warranty and I was given the run around. The problem is now severe and has almost caused me to crash more times than you and I have fingers and toes. I cannot trade this vehicle in because of this problem nor can I find a mechanic or dealership (ha ha ) that can find out where the problem lies. I have been told that the intake motor or the intake gasket need to be replaced but diagnostics cannot back these theories up. Today I nearly hit a telephone pole because the vehicle died and lost power steering while I was making a turn.